Scientists at Baylor University in Waco, Texas, have discovered an unusual metal mass buried at the south pole of the moon, one that likely originated some four billion years ago from a head-on collision with an asteroid.
Researchers say that find will alter our understanding of the moon’s South Pole-Aitken basin, one of the pivotal locations for studying catastrophic impact events.
Published in the journal Geophysical Research Letters, the study titled “Deep Structure of the Lunar South Pole-Aitken Basin” came about through the analyzing data from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission, which took place during 2011 and 2012.
When the research team combined the data with lunar topography results from the Lunar Reconnaissance Orbiter, the large mass was discovered, one which is big enough to weigh down the basin floor by a little less than a kilometre. At about 2,000 km wide the South Pole-Aitken basin is the largest crater known to scientists, with the newly-discovered mass underneath it being large enough to affect the moon’s gravity.
“Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground,” said lead scientist Dr Peter James, in a press release . “That's roughly how much unexpected mass we detected.”
While the true origin of the metal mass is still unconfirmed — another theory is that it’s actually a concentration of dense oxides arising from the last stage of lunar magma ocean solidification —the researcher used computer simulations to theorize that a large asteroid impact could have dispersed the material into the moon’s upper mantle.
“We did the math and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the Moon’s mantle until the present day, rather than sinking to the Moon’s core,” James said.
Below: Gravitational anomaly discovered on moon